Black Swan, Norby 5s and 3s

What is the Mike Bassett Index? - It is a measure of a player's performance. No index is provided where only a single game has been played. Credit is then given for each win and the amount of the credit is linked to the record of the partner. Where a game is won in partnership with a player with a poor record a greater credit is given than if the win was in partnership with a player with a better win record (measured by percentage wins). The total credit is averaged out by the number of games played to determine the Mike Bassett Index. The larger the Index value the better the player - maybe?